The regulation of lymphocyte activation and proliferation

Regulation of T Helper Cell Fate by TCR Signal Strength

T cells are critical in orchestrating protective immune responses to cancer and an array of pathogens. The interaction between a peptide MHC (pMHC) complex on antigen presenting cells (APCs) and T cell receptors (TCRs) on T cells initiates T cell activation, division, and clonal expansion in secondary lymphoid organs. T cells must also integrate multiple T cell-intrinsic and extrinsic signals to acquire the effector functions essential for the defense against invading microbes. In the case of T helper cell differentiation, while innate cytokines have been demonstrated to shape effector CD4⁺ T lymphocyte function, the contribution of TCR signaling strength to T helper cell differentiation is less understood. In this review, we summarize the signaling cascades regulated by the strength of TCR stimulation. Various mechanisms in which TCR signal strength controls T helper cell expansion and differentiation are also discussed.

Identification of Potential Biomarkers for Anti-PD-1 Therapy in Melanoma by Weighted Correlation Network Analysis

Melanoma is the most malignant form of skin cancer, which seriously threatens human life and health. Anti-PD-1 immunotherapy has shown clinical benefits in improving patients' overall survival, but some melanoma patients failed to respond. Effective therapeutic biomarkers are vital to evaluate and optimize benefits from anti-PD-1 treatment. Although the establishment of immunotherapy biomarkers is well underway, studies that identify predictors by gene network-based approaches are lacking. Here, we retrieved the existing datasets (GSE91061, GSE78220 and GSE93157, 79 samples in total) on anti-PD-1 therapy to explore potential therapeutic biomarkers in melanoma using weighted correlation network analysis (WGCNA), function validation and clinical corroboration. As a result, 13 hub genes as critical nodes were traced from the key module associated with clinical features. After receiver operating characteristic (ROC) curve validation by an independent dataset (GSE78220), six hub genes with diagnostic significance were further recovered. Moreover, these six genes were revealed to be closely associated not only with the immune system regulation, immune infiltration, and validated immunotherapy biomarkers, but also with excellent prognostic value and significant expression level in melanoma. The random forest prediction model constructed using these six genes presented a great diagnostic ability for anti-PD-1 immunotherapy response. Taken together, IRF1, JAK2, CD8A, IRF8, STAT5B, and SELL may serve as predictive therapeutic biomarkers for melanoma and could facilitate future anti-PD-1 therapy.

Quantifying the Role of Stochasticity in the Development of Autoimmune Disease

In this paper, we propose and analyse a mathematical model for the onset and development of autoimmune disease, with particular attention to stochastic effects in the dynamics. Stability analysis yields parameter regions associated with normal cell homeostasis, or sustained periodic oscillations. Variance of these oscillations and the effects of stochastic amplification are also explored. Theoretical results are complemented by experiments, in which experimental autoimmune uveoretinitis (EAU) was induced in B10.RIII and C57BL/6 mice. For both cases, we discuss peculiarities of disease development, the levels of variation in T cell populations in a population of genetically identical organisms, as well as a comparison with model outputs.

Individuation and the Organization in Complex Living Ecosystem: Recursive Integration and Self-assertion by Holon-Lymphocytes

Individuation and organization in complex living multi-level ecosystem occurs as dynamical processes from early ontogeny. The notion of living "holon" displaying dynamic self-assertion and integration is used here to explain the ecosystems dynamic processes. The update of the living holon state according to the continuous change of the dynamic system allows for its viability. This is interpreted as adaptation, selection and organization by the human that observes the system a posteriori from its level. Our model concerns the complex dynamics of the adaptive immune system, integrating holon-lymphocytes that collectively preserve the identity and integrity of the organism. Each lymphocyte individualizes as a dynamic holon-lymphocyte, with somatic gene individuation leading to an individual, singular antigen immunoreceptor type, promoting the self-assertion. In turn, the "Immunoception" allows for perception of the environmental antigenic context, thus integration of the holon in its environment. The self-assertion/integration of holon-lymphocyte starts from fetal stages and is influenced by mother Lamarckian acquired historicity transmissions, a requisite for the integrity of the holobiont-organism. We propose a dynamic model of the perception by holon-lymphocyte, and at the supra-clonal level of the immune system functions that sustain the identity and integrity of the holon-holobiont organism.

Signaling pathways involved in the T-cell-mediated immunity against Epstein-Barr virus: Lessons from genetic diseases

Primary immunodeficiencies (PIDs) provide researchers with unique models to understand in vivo immune responses in general and immunity to infections in particular. In humans, impaired immune control of Epstein-Barr virus (EBV) infection is associated with the occurrence of several different immunopathologic conditions; these include non-malignant and malignant B-cell lymphoproliferative disorders, hemophagocytic lymphohistiocytosis (HLH), a severe inflammatory condition, and a chronic acute EBV infection of T cells. Studies of PIDs associated with a predisposition to develop severe, chronic EBV infections have led to the identification of key components of immunity to EBV - notably the central role of T-cell expansion and its regulation in the pathophysiology of EBV-associated diseases. On one hand, the defective expansion of EBV-specific CD8 T cells results from mutations in genes involved in T-cell activation (such as RASGRP1, MAGT1, and ITK), DNA metabolism (CTPS1) or co-stimulatory pathways (CD70, CD27, and TNFSFR9 (also known as CD137/4-1BB)) leads to impaired elimination of proliferating EBV-infected B cells and the occurrence of lymphoma. On the other hand, protracted T-cell expansion and activation after the defective killing of EBV-infected B cells is caused by genetic defects in the components of the lytic granule exocytosis pathway or in the small adapter protein SH2D1A (also known as SAP), a key activator of T- and NK cell-cytotoxicity. In this setting, the persistence of EBV-infected cells results in HLH, a condition characterized by unleashed T-cell and macrophage activation. Moreover, genetic defects causing selective vulnerability to EBV infection have highlighted the role of co-receptor molecules (CD27, CD137, and SLAM-R) selectively involved in immune responses against infected B cells via specific T-B cell interactions.

Self-reactivity on a spectrum: A sliding scale of peripheral B cell tolerance

Efficient mechanisms of central tolerance, including receptor editing and deletion, prevent highly self-reactive B cell receptors (BCRs) from populating the periphery. Despite this, modest self-reactivity persists in (and may even be actively selected into) the mature B cell repertoire. In this review, we discuss new insights into mechanisms of peripheral B cell tolerance that restrain mature B cells from mounting inappropriate responses to endogenous antigens, and place recent work into historical context. In particular, we discuss new findings that have arisen from application of a novel in vivo reporter of BCR signaling, Nur77-eGFP, expression of which scales with the degree of self-reactivity in both monoclonal and polyclonal B cell repertoires. We discuss new and historical evidence that self-reactivity is not just tolerated, but actively selected into the peripheral repertoire. We review recent progress in understanding how dual expression of the IgM and IgD BCR isotypes on mature naive follicular B cells tunes responsiveness to endogenous antigen recognition, and discuss how this may be integrated with other features of clonal anergy. Finally, we discuss how expression of Nur77 itself couples chronic antigen stimulation with B cell tolerance.

Pathologic T-cell response in ischaemic failing hearts elucidated by T-cell receptor sequencing and phenotypic characterization

Aims

A persistent cardiac T-cell response initiated by myocardial infarction is linked to subsequent adverse ventricular remodelling and progression of heart failure. No data exist on T-cell receptor (TCR) repertoire changes in combination with phenotypic characterization of T cells in ischaemic failing human hearts.

Methods and results

Analysis of TCR repertoire with high-throughput sequencing revealed that compared with T cells in control hearts, those in ischaemic failing hearts showed a clonally expanded TCR repertoire but similar usage patterns of TRBV-J rearrangements and V gene segments; compared with T cells in peripheral blood, those in ischaemic failing hearts exhibited a restricted and clonally expanded TCR repertoire and different usage patterns of TRBV-J rearrangements and V gene segments, suggesting the occurrence of tissue-specific T-cell expansion in ischaemic failing hearts. Consistently, TCR clonotype sharing was prominent in ischaemic failing hearts, especially in hearts of patients who shared human leucocyte antigen (HLA) alleles. Furthermore, ischaemia heart failure (IHF) heart-associated clonotypes were more frequent in peripheral blood of IHF patients than in that of controls. Heart-infiltrating T cells displayed memory- and effector-like characteristics. Th1 cells were the predominant phenotype among CD4+ T cells; CD8+ T cells were equally as abundant as CD4+ T cells and produced high levels of interferon-γ, granzyme B, and perforin.

Conclusion

We provide novel evidence for a tissue-specific T-cell response predominated by Th1 cells and cytotoxic CD8+ T cells in ischaemic failing human hearts that may contribute to the progression of heart failure.

Deciphering targets of Th17 cells fate: From metabolism to nuclear receptors

Evidence indicates that reprogramming of metabolism is critically important for the differentiation of CD4 + T lymphocytes, and the manipulation of metabolic pathways in these cells may shape their fate and function. Distinct subgroups from T lymphocytes, such as Th17, adopt specific metabolic programmes to support their needs. Some important metabolic reactions, such as glycolysis, oxidative phosphorylation, are considered important for the differentiation of these lymphocytes. Since their discovery nearly a decade ago, Th17 lymphocytes have received significant attention because of their role in the pathology of several immune-mediated inflammatory diseases such as multiple sclerosis. In this review, it will be discussed as the involvement of T cell metabolism and as metabolic reprogramming in activated T cells dictates fate decisions to Th17. The involvement of nuclear receptors such as RORyt e PPARs in the induction of Th17 cells was also discussed. Understanding the metabolic pathways involved in the differentiation of the distinct subgroups of T lymphocytes helps in the design of promising therapeutic proposals.

Involvement of H-Ras in the adaptive immunity of Nile tilapia by regulating lymphocyte activation

H-Ras is a guanosine triphosphatase (GTPase), which acts as a molecular switch and controls multiple important cellular processes including lymphocyte activation and function. However, regulatory mechanism of adaptive immune response by H-Ras remains unclear in non-mammalian animals. In the present study, we investigated the involvement of H-Ras in lymphocyte activation with a teleost model Oreochromis niloticus. H-Ras from O. niloticus (On-H-Ras) is highly conserved with those from other vertebrates. The mRNA of On-H-Ras showed a wide expression pattern in the lymphoid-tissues and with the highest level in liver. After Aeromonas hydrophila infection, transcription of On-H-Ras was significantly induced on day 8 but came back to basal level on day 16, suggesting that On-H-Ras potentially participated in primary response during the adaptive immunity. Furthermore, On-H-Ras mRNA was obviously up-regulated when leukocytes were activated by T lymphocyte mitogen PHA in vitro. Meanwhile, protein level of H-Ras was also augmented once leukocytes were stimulated with lymphocyte receptor signaling agonist PMA and ionomycin. More importantly, once Ras activity was inhibited by specific inhibitor, the up-regulation of lymphocyte activation marker CD122 was obviously impaired during lymphocyte activation process. Therefore, On-H-Ras regulated lymphocyte activation through both mRNA and protein level. Altogether, our results illustrated the involvement of H-Ras in teleost adaptive immunity via controlling lymphocyte activation, and thus provided a novel perspective to understand evolution of the lymphocyte-mediated adaptive immunity.

Peripheral immune response in the African green monkey model following Nipah-Malaysia virus exposure by intermediate-size particle aerosol

The ability to appropriately mimic human disease is critical for using animal models as a tool for understanding virus pathogenesis. In the case of Nipah virus (NiV), infection of humans appears to occur either through inhalation, contact with or consumption of infected material. In two of these circumstances, respiratory or sinusoidal exposure represents a likely route of infection. In this study, intermediate-size aerosol particles (~7 μm) of NiV-Malaysia were used to mimic potential routes of exposure by focusing viral deposition in the upper respiratory tract. Our previous report showed this route of exposure extended the disease course and a single animal survived the infection. Here, analysis of the peripheral immune response found minimal evidence of systemic inflammation and depletion of B cells during acute disease. However, the animal that survived infection developed an early IgM response with rapid development of neutralizing antibodies that likely afforded protection. The increase in NiV-specific antibodies correlated with an expansion of the B cell population in the survivor. Cell-mediated immunity was not clearly apparent in animals that succumbed during the acute phase of disease. However, CD4+ and CD8+ effector memory cells increased in the survivor with correlating increases in cytokines and chemokines associated with cell-mediated immunity. Interestingly, kinetic changes of the CD4+ and CD8bright T cell populations over the course of acute disease were opposite from animals that succumbed to infection. In addition, increases in NK cells and basophils during convalescence of the surviving animal were also evident, with viral antigen found in NK cells. These data suggest that a systemic inflammatory response and "cytokine storm" are not major contributors to NiV-Malaysia pathogenesis in the AGM model using this exposure route. Further, these data demonstrate that regulation of cell-mediated immunity, in addition to rapid production of NiV specific antibodies, may be critical for surviving NiV infection.

Combined Features Based on Preoperative Controlling Nutritional Status Score and Circulating Tumour Cell Status Predict Prognosis for Colorectal Cancer Patients Treated with Curative Resection

Background: The preoperative controlling nutritional status (CONUT) score and circulating tumour cell (CTC) status are associated with poor prognosis of colorectal cancer (CRC). The aim of the present study is to determine whether the combination of CONUT and CTC (CONUT-CTC) could better predict the prognosis of CRC patients treated with curative resection.

Methods: Preoperative CONUT score was retrospectively calculated in 160 CRC patients who underwent curative resection at Zhongnan Hospital of Wuhan University from 2015 to 2017. Preoperative CTC counts were enumerated from 5 ml peripheral vein blood by a CTCBIOPSY® device. According to the preoperative CONUT and CTC status, the patients were divided into three groups: CONUT-CTC (0), CONUT-CTC (1) and CONUT-CTC (2). The relationship between CONUT score and CTC, as well as the associations of CONUT-CTC status with clinicopathological factors and survival, were evaluated.

Results: Preoperatively, the number and positive rate of CTC were positively correlated with the preoperative CONUT score (P<0.01). An elevated CONUT-CTC score was significantly associated with deeper tumour invasion (P=0.025), lymphatic vessel invasion (P=0.002), venous invasion (P<0.001) and higher pTNM stage (P=0.033). Kaplan-Meier analysis and log-rank tests revealed significant decreases in recurrence-free survival (RFS) and cancer-specific survival (CSS) among CRC patients with CONUT-CTC score of 0, 1 and 2 (P<0.001). In pTNM stage-stratified analysis, high CONUT-CTC score was significantly associated with the poor (P<0.001) and CSS (P<0.001) of patients with stage III disease, but not correlated with the prognosis of patients with stage II disease (RFS: P=0.077; CSS: P<0.090). Further univariate and multivariate analyses showed that CONUT-CTC was an independent factor affecting patients' RFS [hazard ratio (HR)=2.66, 95% confidence interval (CI):1.79-3.96, P<0.001] and CSS (HR=3.75, 95%CI: 2.14-6.57, P<0.001). In time-dependent receiver operating characteristics (ROC) analyses, CONUT-CTC score had a higher area under the ROC curve (AUC) for the prediction of RFS and CSS than did preoperative CONUT score or CTC status.

Conclusion: The preoperative CONUT-CTC score is associated with tumour progression and poor prognosis in patients with CRC treated with curative resection, indicating that better information on CRC prognosis could be obtained from combined preoperative host immune-nutritional status and CTC detection.

c-Raf participates in adaptive immune response of Nile tilapia via regulating lymphocyte activation

RAF proto-oncogene serine/threonine-protein kinase (c-Raf) is a MAP kinase kinase kinase (MAPKKK) that participates in the Erk1/2 pathway and plays an important role in lymphocyte activation. However, the study on how c-Raf regulates adaptive immunity in non-mammal is still limited. In present study, based on analysis of sequence characteristics of c-Raf from Oreochromis niloticus (On-c-Raf), we investigated its regulation roles on teleost lymphocyte activation. The On-c-Raf was highly conserved during evolution, which was composed of a Raf-like Ras-binding domain (RBD), a protein kinase C conserved region 1 (C1) domain and a serine/threonine protein kinase catalytic (S_TKc) domain. Its mRNA showed a wide distribution in tissues of O. niloticus and with the highest expression in gill. After Aeromonas hydrophila infection, during the adaptive immune stage transcription level of On-c-Raf was significantly upregulated on day 8, but came back to original level on day 16 and 30, suggesting the potential involvement of On-c-Raf in primary response but not memory formation. Furthermore, On-c-Raf mRNA in leukocytes of Nile tilapias was obviously induced by in vitro stimulation of T cell mitogen PHA. More importantly, in vitro stimulation of lymphocytes agonist PMA augmented phosphorylation level of On-c-Raf in leukocytes detected by western-blot and immunofluorescent. Thus, c-Raf regulated lymphocyte activation of Nile tilapia on both mRNA and phosphorylation level. Together, our results revealed that the c-Raf from teleost Nile tilapia engaged in adaptive immune response by regulating lymphocytes activation. Since the regulatory mechanism of lymphocyte-mediated adaptive immunity is largely unknown in teleost, our study provided important evidences to understand teleost adaptive immunity, and also shed a novel perspective for the evolution of adaptive immune system.

Towards multiscale modeling of the CD8+ T cell response to viral infections

The CD8⁺ T cell response is critical to the control of viral infections. Yet, defining the CD8⁺ T cell response to viral infections quantitatively has been a challenge. Following antigen recognition, which triggers an intracellular signaling cascade, CD8⁺ T cells can differentiate into effector cells, which proliferate rapidly and destroy infected cells. When the infection is cleared, they leave behind memory cells for quick recall following a second challenge. If the infection persists, the cells may become exhausted, retaining minimal control of the infection while preventing severe immunopathology. These activation, proliferation and differentiation processes as well as the mounting of the effector response are intrinsically multiscale and collective phenomena. Remarkable experimental advances in the recent years, especially at the single cell level, have enabled a quantitative characterization of several underlying processes. Simultaneously, sophisticated mathematical models have begun to be constructed that describe these multiscale phenomena, bringing us closer to a comprehensive description of the CD8⁺ T cell response to viral infections. Here, we review the advances made and summarize the challenges and opportunities ahead. This article is categorized under: Analytical and Computational Methods > Computational Methods Biological Mechanisms > Cell Fates Biological Mechanisms > Cell Signaling Models of Systems Properties and Processes > Mechanistic Models.

Prognostic value of pretreatment systemic immune-inflammation index in patients with gastrointestinal cancers

BACKGROUND

Numerous studies have reported the relationship between systemic immune-inflammation index (SII) and prognosis in gastrointestinal (GI) cancers, but no consensus has been reached. We aimed to systematically evaluate the prognostic value of SII in patients with GI cancers.

METHODS

Relevant published papers regarding the prognostic value of SII in patients with GI cancers were obtained from a number of electronic databases. The overall hazard ratios and the corresponding 95% confidence intervals (95% CIs) were calculated using a fixed or random effects model to assess the relationship between SII and prognosis through Stata SE 12.0.

RESULTS

A total of 24 eligible published articles with 9,626 patients were included. From the pooled results, we found that high SII indicated worse overall survival (OS) in patients with GI cancers (HR = 1.52, 95%CI: 1.29-1.74). And patients with high SII had poorer disease-free survival (HR: 2.28, 95% CI: 1.46-3.10), time to recurrence (HR: 1.70, 95% CI: 1.11-2.30), and recurrence-free survival (HR: 1.60, 95% CI: 1.19-2.00) when compared with those with low SII values.

CONCLUSIONS

SII might serve as a noninvasive and powerful tool for predicting survival outcome in patients with GI cancers.

The Channel-Kinase TRPM7 as Novel Regulator of Immune System Homeostasis

The enzyme-coupled transient receptor potential channel subfamily M member 7, TRPM7, has been associated with immunity and immune cell signalling. Here, we review the role of this remarkable signalling protein in lymphocyte proliferation, differentiation, activation and survival. We also discuss its role in mast cell, neutrophil and macrophage function and highlight the potential of TRPM7 to regulate immune system homeostasis. Further, we shed light on how the cellular signalling cascades involving TRPM7 channel and/or kinase activity culminate in pathologies as diverse as allergic hypersensitivity, arterial thrombosis and graft versus host disease (G_VHD), stressing the need for TRPM7 specific pharmacological modulators.

Multiplexed Division Tracking Dyes for Proliferation-Based Clonal Lineage Tracing

The generation of cellular heterogeneity is an essential feature of immune responses. Understanding the heritability and asymmetry of phenotypic changes throughout this process requires determination of clonal-level contributions to fate selection. Evaluating intraclonal and interclonal heterogeneity and the influence of distinct fate determinants in large numbers of cell lineages, however, is usually laborious, requiring familial tracing and fate mapping. In this study, we introduce a novel, accessible, high-throughput method for measuring familial fate changes with accompanying statistical tools for testing hypotheses. The method combines multiplexing of division tracking dyes with detection of phenotypic markers to reveal clonal lineage properties. We illustrate the method by studying in vitro-activated mouse CD8⁺ T cell cultures, reporting division and phenotypic changes at the level of families. This approach has broad utility as it is flexible and adaptable to many cell types and to modifications of in vitro, and potentially in vivo, fate monitoring systems.

Possible role of circulating endothelial cells in patients after acute myocardial infarction

Acute myocardial infarction (AMI) occurs as a result of insufficient myocardial perfusion leading to cell necrosis. This is most commonly due to the obstruction of the coronary artery by ruptured atherosclerotic plaque and thrombosis. Damaged ischemic and necrotic myocardial cells release pro-inflammatory substances in tissue and plasma, leading to a systemic inflammatory response. Profound systemic inflammatory response during ischemia/reperfusion injury causes disruption of endothelial glycocalyx and detachment of endothelial cells that express von Willebrant factor (vWF). We hypothesize that circulating vWF+ endothelial cells could act as antigen presenting cells which interact with T and NK cells directly, by cell to cell contact and indirectly by cytokine and chemokine secretion, leading to the immune response towards inflammation. Analyzing the frequency, phenotype and pro-inflammatory substances produced in circulating vWF positive (+) cells in patients with AMI could be beneficial to determine the severity of the pro-inflammatory response, according to the level of endothelial dysfunction in the early period of AMI. To evaluate these hypotheses, we suggest to determine frequency, phenotype, and ability of cytokine/chemokine production in circulating vWF+ endothelial cells by simultaneous surface and intracellular cell staining, and flow cytometry analysis. Secretion of pro-inflammatory cytokines and chemokines, pro-atherogenic substances and the components of glycocalyx might be measured in supernatants of magnetically separated or sorted vWF+ endothelial cells, as well as in the serum of a patient with acute AMI by enzyme linked-immunoassay tests. The interaction of increasing concentrations of isolated circulating vWF+ endothelial cells and cognate T and NK cells might be investigated by lymphocyte proliferation rate, cytotoxic mediators' expression, and cytokine production. If our hypothesis is correct, characterization of circulating vWF+ endothelial cells could grant us greater insight into their role in pathophysiology of AMI and the degree of myocardial damage.